HAZARDS CAUSED BY GEOLOGIC PROCESSES / EARTH AND LIFE SCIENCE / SCIENCE 11 - MELC 15

Summary

This video explores the hazards caused by geologic processes such as earthquakes, volcanic eruptions, and landslides. It discusses the causes and effects of these natural disasters, including ground shaking, tsunamis, liquefaction, and subsidence from earthquakes, as well as pyroclastic flows and lahars from volcanic eruptions. Landslides are also examined, detailing the five types of slope movements: falls, topples, slides, spreads, and flows. The video emphasizes the importance of understanding these hazards to mitigate their impact on communities and infrastructure.

Takeaways

• 🌏 Earthquakes are caused by vibrations from rock breaking under stress, which travel as seismic waves.
• 📏 The strength of earthquakes is measured by magnitude (energy released) and intensity (effects on the surface and structures).
• 🏗️ Earthquakes can cause significant damage to buildings, bridges, and dams, and can also trigger tsunamis and landslides.
• 🌋 Volcanic eruptions involve the release of lava, ash, and gases through an opening in the Earth's crust, and are often associated with tectonic plate boundaries.
• 🔍 The Philippines, located on the Ring of Fire, experiences frequent earthquakes and volcanic activity due to its tectonic setting.
• 🚨 Volcanic eruptions can lead to various hazards including earthquakes, ground fracturing, and the generation of lahars which can persist for decades.
• 🏞️ Landslides are the movement of rock, debris, or earth down a slope, causing harm to communities and infrastructure.
• ⛈ Factors triggering landslides include typhoons, changes in water levels, earthquakes, volcanic activity, and human disturbances.
• 🔑 There are five modes of slope movement in landslides: falls, topple, slide, spread, and flows, each with distinct characteristics.
• 📚 Understanding geological hazards is crucial for community safety and disaster preparedness.

Q & A

What is an earthquake and how does it occur?

An earthquake is caused by vibrations from rocks breaking under stress. The vibrations travel to the Earth's surface as seismic waves, releasing a lot of energy. The point where an earthquake originates underground is called the focus, and the location directly above it on the Earth's surface is the epicenter.

What are the two ways to measure the strength of an earthquake?

Earthquakes are measured in two ways: magnitude and intensity. Magnitude is proportional to the energy released by an earthquake and is represented by Arabic numbers. Intensity refers to the severity of the earthquake’s effects on the Earth's surface, humans, and structures, and is represented by Roman numerals.

What are the major effects of earthquakes?

The major effects of earthquakes include ground shaking, tsunamis, subsidence (sinking of the ground), lateral spreading (movement of soil masses), and liquefaction (loosening of soil due to ground movement). These can damage buildings, bridges, dams, and destabilize cliffs and sloping ground.

What are the two major sources of earthquakes?

The two major sources of earthquakes are tectonic earthquakes, which occur when plate boundaries move and grind against each other, and volcanic earthquakes, which occur due to the injection or withdrawal of magma.

How do volcanic eruptions occur?

Volcanic eruptions occur when magma containing dissolved gases rises through cracks in the Earth's crust. The magma escapes through an opening called a volcano, releasing lava, volcanic ash, and gases. Many active volcanoes are located along the Pacific Ring of Fire, where tectonic plates meet.

What are the major hazards of volcanic eruptions?

Major hazards of volcanic eruptions include earthquakes, ground fracturing, swelling of the ground, gas emissions, and pyroclastic flows (hot gas and ash moving down slopes). After eruptions, heavy rainfall can generate lahars (volcanic mudflows), which can continue for decades.

What is a landslide and what causes it?

A landslide is the movement of a mass of rock, debris, or earth down a slope. Factors such as typhoons, snowmelt, changes in water level, stream erosion, earthquakes, volcanic activity, wildfires, and human disturbances can initiate landslides.

What are the five modes of slope movement in landslides?

The five modes of slope movement in landslides are falls (collapse of material from a cliff), topples (rotation or tilting of rock), slides (displacement of material along shear surfaces), spreads (horizontal movement), and flows (movement triggered by rainfall or snowmelt).

What are the major effects of landslides on human communities?

Landslides can cause property damage, injuries, and even death. They can also damage water supplies, fisheries, sewage systems, forests, dams, and roadways, with effects lasting for years.

How can volcanic eruptions and earthquakes affect the Philippines?

The Philippines, located along the Pacific Ring of Fire, is prone to both earthquakes and volcanic eruptions due to its tectonic setting. Historical events, like the 1990 Luzon earthquake and the 1991 Mount Pinatubo eruption, have caused significant destruction and affected many lives.